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K[Cr(C4H6N2O3)2·C4H6N2O2·2H2O, Mr = 501.44, crystallizes in the mono-clinic space group P21/c, with a = 11.364(4), b = 12.333(6), c = 14.630(7) A, β = 107.39(4)°, V = 1956.6 A3 and Z = 4. The structure was solved by direct methods and converged to a final R value of 0.062 (Rw = 0.072). The incorporation of piperazine-2,5-dione, formed by self-condensation of glycylglycine, in the crystal structure results in some changes in bond lengths and bond angles and a many-fold increase in the luminescence lifetime of the chromium complex, relative to the structure without piperazinedione.

Coordination of substituted pyridine N-oxides with oxovanadium /IV/ cations, noting stoichiometric variations with changes

It is recommended that a self-consistent set of sigma constants be used to obtain linear free energy relations with pyridine 1-oxides rather than using adjusted benzoic acid sigma constants. These recommended constants are derived from the literature values of the acid dissociated constants of the protonated substituted pyridine 1-oxides. A survey and discussion of linear free energy relations using these new constants (σPyNO) is given. Comparisons of correlations using adjusted benzoic acid sigma constants and (σPyNO) are presented.

Eulytite, Bi4(SiO4)3, is a cubic mineral, S.G. = \( I\overline {43} d\), with irregular (BiO6) polyhedra and (SiO4) tetrahedra. With the substitution of P for Si, the charge balancing (3A2+ + Ln3+) for 4Bi is possible. Eulytite structure phosphates, A3Ln(PO4)3, are one of the ternary phases that form in the A0-Ln203-P205 systems currently under investigation in our laboratories. Synthesis and crystal data for phosphate eulytites where A = Ca, Sr, Ba, Pb and B = La→Lu, Y, Sc, In are included here.

Laser synthesized silicon powders have been used to make reaction bonded silicon nitride samples. Maximum hardness (11.3 GNm−2), fracture toughness (3.6 MNm−3/2), pore size (Hg porosimetry 50–300Å radius) and strength (∼460 MNm−2) values reflect the superior microstructures that are observed. With anaerobic anhydrous processing, these powders nitride to completion in less than 7 hours at 1400°C.